Isolation of bacteriophages and their application to control Pseudomonas aeruginosa in planktonic and biofilm models

Pseudomonas aeruginosa is frequently identified as a cause of diverse infections and chronic diseases. It forms biofilms and has natural resistance to several antibiotics. Strains of this pathogen resistant to new-generation beta-lactams have emerged. Due to the difficulties associated with treating chronic P. aeruginosa infections, bacteriophages are amongst the alternative therapeutic options being actively researched. Two obligatorily lytic P. aeruginosa phages, vB_PaeM_MAG1 (MAGI) and vB_PaeP_MAG4 (MAG4), have been isolated and characterized. These phages belong to the PAK_Pllikevirus genus of the Myoviridae family and the LITlvirus genus of the Podoviridae family, respectively. They adsorb quickly to their hosts (similar to 90% in 5 min), have a short latent period (15 min), and are stable during storage. Each individual phage propagated in approximately 50% of P. aeruginosa strains tested, which increased to 72.9% when phages were combined into a cocktail. While MAG4 reduced biofilm more effectively after a short time of treatment, MAGI was more effective after a longer time and selected less for phage-resistant clones. A MAGI-encoded homolog of YefM antitoxin of the bacterial toxin-antitoxin system may contribute to the superiority of MAGI over MAG4. (C) 2016 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.